It was quite a serious accident, _____caused by careless driving.
| A．which I think was | B．I think which was |
| C．which I think it was | D．I think which it was |
--I’m going to the States?
--How long ________ you________ in the States?
| A．are; stayed | B．are; staying | C．have; stayed | D．did; stay |
Rather than _________ on a crowded bus, he always prefers _________ a bicycle.
| A．ride; ride | B．riding; ride | C．ride; to ride | D．to ride; riding |
__________ of the students who took part in the military training is 450.
| A．A number | B．A lot | C．Lots | D．The number |
He realized she was crying ________ his words.
| A．because | B．because of | C．as | D．since |
Mary, ________ here. Everybody else, stay where you are.
| A．come | B．comes | C．to come | D．coming |